This invention relates generally to microwave apparatus, and more particularly to a crossed field meander line slow-wave circuit device.
It has been determined in prior art crossed field meander line circuits, for example U.S. Pat. No. 3,904,994, entitled "Meander Line Circuit With An Interdigital Ground Plane", and U.S. Pat. No. 3,925,738, entitled "Rail or Pedestal Mounted Meander Line Circuit For Cross-Field Amplifiers", C. D. Bates et al that removal of the dielectric between meander line segments results in several advantages heretofore unavailable, namely, it eliminates the effects of sputtering which would otherwise act as a collection surface for sputtered metal, it eliminates extraneous RF dielectric loading of the RF wave formed by the meander line, and it reduces segment-to-segment capacitance of the metallic meander line which in turn reduces the dispersion and increases the bandwidth of the device. In the referenced patents there are shown meander line slow-wave circuit devices in which the dielectric support includes a raised surface portion which is shaped identically with the metallic conductor material disposed thereon. U.S. Pat. No. 3,925,738 in FIG. 4 shows conductive shielding vanes between segments of the meander line.
U.S. Pat. No. 4,074,211 entitled "Dielectric Substrate for Slow Wave Structure" by C. D. Bates is directed to meander line slow-wave circuitry consisting of a metallic ground plane, a dielectric substrate contigous with said ground plane, and a serpentine meander line conductor located on the dielectric substrate. The substrate is ladder shaped, having a plurality of regularly spaced transverse vane segments intersecting a pair of opposing longitudinal vane segments and upon which said meander line conductor is disposed whereupon certain portions of the vane segments are exposed while providing slot-like separations in the dielectric substrate between adjacent segments of the meander line conductor.
Advantages of the shaped-substrate circuit supported on individual bars are (1) the parts count is greatly reduced, thus reducing the cost of parts and of assembly; and (2) circuits for higher frequency are possible. When the circuit is supported on individual dielectric bars, the circuit dimensions are limited by the size of bars which are practical to manufacture and assemble.